Steam heating system



April 4, 1939- A. F. UNDERwooD 2,153,108 l STEAM HEATING SYSTEM FiledDec. 30, 1952 2 SheetS-Sheet l /f gmmntoz /4 l Wmy,%my%.

April 4, 1939. A F. uNDERwooD STEAM HEATING SYSTEM 2 Sheets-*Sheet 2Filed Dec. 30, 1932 Patented Apr. 4, 1939 @UNITED STATES APATENT OFFICEY STEAM HEATING SYSTEM Arthur F. Underwood, Detroit, Mich., assignor, by

mesne assignments, to General Motors Corporation, Detroit,uMich., a.ycorporation of Dela- Application December 3o, 1932, serial No. 649,495

` l claims. (ci. zar-12.3)

amount of liquid inthe steam generator `or boiler so as to maintain asubstantially constant low 'pressure regardless of changes in exhaustgas temperatures whichmay varyfrom an average of 500 F. at low carspeeds to 1350" F. at higher car speeds. i f I I,

As willbe more fully described hereinafter, Vthis control of pressure inthe system consists in the provision of a `controlor expansion tankwhich is open to the atmosphere and is positioned above l and connectedto the steamgenerator so that when any pressure is developed. in thegenerator,

" liquid will beforcedtherefrom. upwardly toward or intothistanktothereby reduce the quantity of liquid whichis available ink the steamgenerator and therebylimit the maximum in pressure which may beldeveloped anywhere in the systemr so that it will never exceed thatpressure required to raise the liquid from the generator to theexpansionv tank. Otherl features of my invention and theA particularadvantages of the same will appear from the following detaileddescription of the structure and operation-ofthe embodiments illustratedin the accompanying drawings, in which.: y

Figure 1 is a side elevation with 'parts in section of one embodiment ofmy' heating; system as applied to an automotive vehicle.`

Figure 2 is an enlarged vertical sectional view takenon the line 2-2Vof.Figure '1 A Figure 3 is a` sideA elevation 'partly in section ofthe'expansion tank and condenser taken on l-ine 3-"-3 of Figurel".`

Figure 4 is a 'sideelevationsimilar toFigure l but illustrating afurtherembodiment of my. heating system. Figure 5 is an enlarged horizontalsectional view taken on the line 5 5 of Figure 4.

Figure 6 is a sectional view taken on line `E---li of Figure 5.

Referring rst to both'Figure 1 and Figure 4, there hasl been showndiagrammatically only those portions of the usual automotive vehiclewhich are necessary for an understanding of the application of myimproved heating system thereto. The internal combustion engine isindicated generally` at l as located in the engine compart- 4ment whichis separated from the body compartment by the usual dash 2 and floorboard 3. This engine includes the usual exhaust manifold 4 and the usualexhaust pipe of which there is shown a portion 5. It will be understoodthat the engine is also provided with the usual cooling fan (not shown)and in this and other respects is generally similar to standardpractice.

Referring now to the specic embodiment of my invention which has beenillustrated in Figures 1, 2 and 3, the principal parts of the heatingsystem consist of a steam generator or boiler unit 6, a heater unitindicated generally at 1 and an expansion tank and condenser unit 8.

The boiler 6 preferably consists of steel or alloy tubing which isattened and secured within the exhaust pipe preferably beneath the pointof attachment thereof to the exhaust manifold. As indicated, thisportion of the exhaust pipe is generally extended vertically so that theboiler s may be placed in a substantially vertical position to permitthe attachment of a steam supply conduit adjacent its upper end and acondensate return conduit adjacent its lower end. To secure the boilerto the exhaust pipe and provide for the steam supply and condensatereturn thereto, an externally threaded fitting 1 may be welded to theboiler adjacent each end thereof and in assembly the boiler may beinserted from the upper end of the exhaust pipe and the fittings passedoutwardly throughholes which are provided in the exhaust pipe and thenclamped thereto by means of a nut 8 externally applied to each fitting,suchas is indicated with reference to the upper tting or connection tothe boiler which is located below the upper end of the boiler for areason which will be given in the description of the operation of theentire system.

The upper fitting of the boiler is provided with a metal extension 9 towhich is secured at its outer end a section of rubber hose I0 whichfunctions both as a steam supply and condensate return conduit.Intermediate its ends the extension 9 is connected to a separatecondensate return conduit ll which extends downwardly to be connectedwith the lower end ofthe boiler. Withinthe extension 9 there is a shortsection of metal tubing I2 extending. from the fitting to a point beyondthe connection to the return conduit Il so as to admit the steam supplyto the common conduit III at a point beyond the separate return conduitfor the condensate, and to"y further prevent the steam from interferingwith the return of condensate, the tube I2 is shown as located above thecenter of both the boiler fitting 'I' and the extension 9. Forconvenience the filling the system with only a .predetermined amount ofliquid, there is provided a removable V filling capy or plug I3 adjacentthe upper end of` the separatereturn conduit II.

The `lower fitting of the boiler has not. been shown in detail but itshould be noted that the lower end of the boiler and the fitting orextension yI4 thereof is inclined downwardly and the return conduit I Iis connected thereto adjacent the boiler at a point intermediate theboiler and the connection of the fitting or extension I4 to the controlconduit -I-E leading to the expansion tank and condenser unit 8. Theheater unit 'I has been shown as generally` similar to units now used inhot water car heatersystems, being mounted on the dash 2 within the,

body compartment and consisting of a radiator IB with an electric motorI1 and fan I8 for' creating a forced circulation. of air through theradiator. It will be readily ,understood that this particular type ofheatingI unit isvnot an vessential feature of my heating system but anyknown type of radiator unit may be employed and located either withinthe body compartment or outside of the same withsuitable distributingducts for the heated air, and with or without forced circulation.

In the type of heater unit which has been illustrated, any conventionalradiator core may be used, but preferably one in which the passages areof fairly lowvrestrictiom since the condensate must run downwardlythrough the same passages through which the steam rises to the top ofthe radiator, As clearly indicated in Figure 1, the

steam supply and condensate return conduit III is connected to the lowerend of the radiator I6 and the radiator is provided at its upper endwith an opening I9 which in the embodiment of my invention illustratedin Figures 1 to 3 is connected tothe expansion tank and condenser unit 8by conduit.

Within the upper'end lof 'the radiator is a thermostatically operatedvalve to substantially close'the.opening I9 when the radiator becomeslled with steam. `This valve is shown in Figure 2 as consisting ofl aflat disc 2l mounted beneaththe opening I9 on the free end of a bi-metalarm 2`2 constituted by stripsof metal of such different characteristicsof expansion that the disc 2| willy move to substantially close theopening I9 at a temperaturewithin the radiator of approximately 210 F.valve has been described as substantially closing the opening in theupper end of the radiator, sincethere is some smallieakage past the typekof valve illustrated which has a definite function which will be notedhereinafter in the description of the operation of the entire System.

o The `expansion tank and condenser unit 8 is shown in Figure 3 asconsisting `of the tank 2i land superposed condenser 22 within ythecasing 2 3. The condenser may comprise merely a small sectionof radiatorcore open at its bottom to the tank 2Iand opening atits top to theatmosphere throughthe casing 2'3 by means of the bent tube 24, As shownin'. Figures 1 and 3, the fluid control conduit I5 from the boilerlsconnected to the bottom of the tank 2I andthe conduit 20 haustgases'will soon thaw out from the radiator is connected to the tank 21|'adjacent its bottom.

In describing the operation of the embodiment shown in Figures 1 to.3,it is desired to first call attention to the location of the separatereturn conduit' II and the lower portion of the conduit I5 as adjacentto each other and to the exhaust pipe 5, and also to the relativelocation of the lradiator unit 1 and expansion tank and condenser lunit8 horizontally above the boiler I so that complete drainage will beafforded to the latter. It is also preferable to position the'expansiontank and condenser unit 8 adjacent the forward end of the engine I inproximity to the usual engine cooling fan (not shown) so that such unitwill be cooled by the circulation of lengine'cooling air.

It has been found that certain disadvantages which accompany the use offi anti-freezing solutions-the present system has been so designed asto prevent injury and operate properly'even though freezing of .thewater shouldk occur during periods in whichthe heating system is not inuse, or in other words. when the'engine is not in operation. Let usassume, for instance. that the heating system has Just been installed.'Ihe lling plug I3 would beremoved and an l amount oi' water introduceduntil over-flow occurs through the filling opening which wouldthereafter be closed `by the filling plug. It will be noted that thisfilling plug opening is so located that the maximum amount' of water'which may be introduced into the system will be contained within themajor `portionof the boiler within the exhaust pipe and those portionsof the conduits II and I 5 which are adjacent the exwater is preferablythe best medium for producing steam, and in view oi haust pipe 5.Therefore. if this liquid freezes, it

lmay expand slightly without injury to the system and whenever theengine is started the hot exthe entire body of liquid. y

In normal operation, when, the engine is started, the hot exhaust gasescoming into contact with the boiler surface heats the liquid in theboiler vforming steam winch passes through the steam supply conduit I0to the radiator I6, where it is condensed by heat lradiation which isfacilitated by-the air circulating fan. This condensate returns throughlthe conduit I0 to the lover-now pool formed within the extension lfrom` where it is returned to the bottom of the boilerthrough the returnconduit II.

The boiler 6 is constructed of a substantially vertical tube which has as uiliciently large passage when flattened to ail'ord the.. minimumrestriction, since if too restrictive, the sudden formation of steam atthe entering point will push the incoming liquid'from the boiler insteadof pushing the steam to the heater unit. Also the steam outlet isiocatedseveral inches from 4the top of the boiler vso that any liquid whichmight be forced to the topy of theboiler -by rapid steam* formation will`not pass into the steam supply conduit but will be turned into steam orback to the lower part of the boiler.

lialll As the radiator I6 iirst becomes illled with steam, the airwithin the radiator, is forced through the conduit 20 and expelledthrough the tank 2| -and condenser t2 to the atmosphere. Whensubstantially all air end of the'radiator to prevent the escape ofsubstantially all of the steam .vapor in the radiator.

e has been expelled,` y contact of the steam with the bi-metal arm-22 yj substantially closes the opening I9 in the upper aisance gas wouldrise to the top of the radiator andy gradually decrease the 'steamcapacity sufilciently to seriously interfere with the heat radiationfrom the radiator, making it necessary to provide some means for escapeof this gas. In addition to possible impurities in'the water to producethis gas, it has been primarily thought tol be formedyby liberation ofhydrogen by the reaction of the water with the iron of the boiler athigh temperal f tures. Regardless of the real source oi' this fixed sgas, -it will beapparent that Ithe provision of some leakagev past thethermostaticvalve in the upper end of the radiator permits this gas toescape to the atmosphere through the condenser 22 whichprevents'such'small-amount of steam as might also-escape past thethermostatlc valve from being lost with consequent reduction in theamount of liquid which would require the addil tion. of more liquid atindeterminate intervals,

, las

`It will be obvious that withithe exhaust temperatures which areavailable `for steam generation, more steam will be generated than canbe condensed in the'ra'diator and the expansion tank andv condenserunit-3 is therefore connected to the bottom of thefboiler by -theconduit i 5 so thatthe liquid level `within the boiler will be loweredautomatically on thegeneration of any pressure within'the upperend ofthe boiler by forcing the liquid from the bottom ofV the boiler upwardlytoward or intojthe expansion tank, and at high engine speeds. it will befound that there' is verylittle liquidin the boiler and most of it willbe inthel Aexpansion tank. Also (it will be .readily seen that when theradiator is completely filled with steam,v a pressure will be maintainedwhichisequalto the head oi' liquid within .theV expansion.4 tank theVconduit from the same'to; the 'boiler.` It will also be obvious thatwhenever the pressurefalls below this maximum,

` liquidwill be returned to the boiler from the expansion tank and itsconnecting conduit and a pointof pressure equilibrium will be'almostconstantly maintained.

` ,l In addition to preventing the Vescaper of any steam vapors whichmay leak past the thermostatically operated valve in the radiator, thecondenser 22' is provided above the expansion tanky 2|' to prevent theloss of any vapors which may begiven ou by the liquid within this tank,and as 'has -been noted hereabove, the efficiency of the condenser ispreferably increased bylocating the same adjacent the engine coolingfan` Ordinarily, the liquid in Ithe expansion tank is at a sumcientlylow temperature that no vaporswould be produced therein, but if theengine is first started at high speeds,rsubstantially all of the liquidin' the boiler would be heated and on generation of steam, a largeproportion of ythis heated liquidl would be suddenly forced to theexpansion tank. Under these conditions, however, the condenser wouldfunction to substantially entirely prevent vaporloss. 'I'he'escape ofvapor is further prevented or reducedby. returning thehighly heatedvcondensate from the radiator to the boiler at a point between theboiler and the connection to tothe expansion tank and 4condenser unit'and the provision of a small leakage tank and condenser 3I mounteddirectly on the top of the heater unit 1. 'I'here has also been providedan accessory reserve tank 32 to facilitate filling or replenishing thesupply of liquid in thesystem.

With reference to the small leakage tank 30 and condenser 3l, which isopen to the atmosphere, the same functions in conjunction with thethermostatically operated valve within the upper end of the radiator toprovide for the escape of air from the radiator until the latter becomesillled with steam and thereafter functions to receive and condense suchsmall leakage as there may be past the thermostatically operated valveand permits the escape of any gas which may be generi ated in thesystem. Such steam vapors as may leak pastv the thermostaticallyoperated valve and .be condensed by the small condenser 3| will beA`retained in the leakage tank 30 and returned to the system Wheneverthe 'upper end of the radiator cools suiliciently to permit anysubstantial opening of the thermostatically operated valve.

'Ihe reserve tank 32 is preferably located on the dash within the enginecompartment and is connected to the system by conduit 33 at a point inthe condensate return conduit Il corresponding to the location of thefilling opening and plug in the embodiment of my invention shown inFigure l. A valve unit 34 is provided in the conduit 33 adjacent theconnection to conduit Il. `'I'his valve unit 34, as shown in detail inFigures 5 and 6, includes in addition to the liquid passage 35 leadingto the conduit Il, a furtherv passage 36 opening to the atmosphere. Boththe passage 35 and the passage 36 are adapted to be openedsimultaneously by manual rotation of the plug valve 31 which isscrew-threaded on the valve unit as at 38. As will be apparent, when thevalve is operated to admit liquid to the system, the liquid will runoutof the passage 38 as any gas caused by decomposition and which mighteventually interfere with proper operation of the system by restrictingthe heating capacity of the radiator would not be retained in the systembut would be exhausted by leakage through the expansion tank andcondenser unit of Figure l or the small leakage tank and condenser unitof Figure 4.

No means has been provided in either of the illustrated systems toentirely stop operation thereof, since this is considered unnecesarywith the type of heating unit shown in which substantially no heat isdissipated by the radiator without the forced air circulation affordedby the fan which may be turned off br its speed regulated in accordancewith usual practice. 4Iii found desirable, however, with this or othertypes of heating units, a manually operable shut-oft valve could beprovided and located, for instance, in the steam supply and condensatereturn conduit.

From the above detailed description, it will be seen that a very simpleand yet highly effectivev While in accordance with the vprovisionsof'the statutes I have illustrated and described herein two embodiments ofmy invention, it will be apparent that changes maybe made in the formofv the systems disclosed without distinguishing' from the spirit of myinvention as set forth in the appended claims.- certain features of myinvention may be used to advantage without a corresponding use of otherfeatures.

u What I claim as my invention is:

.0 a vaporizable liquid and associated with said 'exhaust pipe so as tobe heated by the exhaust gases passing therethrough, means connectingsaid generator to said radiator forthe supply of steam` to the radiatorand the return of condensate to the generator, and means toautomatically control the quantity of steam generatedby automaticallyvarying the amount of liquid in said generator comprising a ventedexpansion tank, means connecting said generator to said expansion tankinto which liquid will be forced by steam pressure developed in saidgenerator, said expansion tank being continuously vented to theatmosphere through an air cooled condenser to condense any vapors fromthe liquid in said tank and return the condensate to the system. Y

2. In a steamheating system, thecombination with a boiler adapted tocontain a `vaporizable liquid and generate steam on application of heatthereto,a radiator, means connecting said boiler to said radiator forthe supply of steam to the u radiator and the return of condensate tothe boiler, an expansion tank, means connecting said tank to said boilerto receive liquid therefrom, a vented condenser on said expansion tankto receive steam and return the condensate to the system, and meansconnecting said radiator to said condenser with a thermostaticallyoperated It will also be yapparent that valve in said radiator which isadapted to substantially close said connecting means to said condenserwhen said radiator becomes fllled with steam.

3. A steam heating system for motor vehicles comprising in combinationwith the vehicle en-v gine and its exhaust pipe, a radiator for thevehicle, a steam generator adapted to contain a vaporizable liquid andassociated ,with said exrhaust pipe so as to be heated by the exhaustYgases passing therethrough, means connecting said generator: to saidradiator for the supply o! steamto the radiator and the return ofcondensate to the. generator, and means to automatically control thequantity of steam generated by automatically varyingthe' amount ofliquid in said generator, comprising-an expansion tank and condenserunit connected to said generator to receive liquid therefrom, saidexpansion tank and condenserv unit being positioned adjacent the frontend of the vehicle engine so as to be cooled by the circulation of airthereover.

4. In a steamheating system, the combination with a boiler adapted tocontain a' vaporizable liquid and generate steam on application of heatthereto, a radiator, means connecting said boiler to said radiatoriorthesupply of steam to the radiator and the. return ofcondensate to theboiler, a vented expansion tank connected to said boiler, and means tosupply liquid to said system comprising a separate reserve tank andmeans including a. manually operable valve for connecting said reservetank with said system, said valve being provided with an overflowpassage which is opened to the atmosphere when-said reserve tank isplaced in communication'with said system to limit the amount of ,liquidwhich may be suppliedto said system to that which may be containedtherein below Athe horizontal level of said valve passage.

5. In alsteam heating system, the combination with a boiler adapted tocontainv a vaporizable liquid and generate steam on application of heatthereto, a radiator, means connecting said boiler to said radiator forthe supply of steam to the radiator and the return of condensate to theboiler, alvented expansion tank so connected to said boiler as toreceive liquid therefrom and automatically control the amount of liquidavailable for steam generation therein, a, relatively restrictedconnection from a normal point of air accumulation in said radiator tosaid expansion tank, and a thermostatically operated valve in saidradiator to substantially close the connection of said radiator to saidexpansion tank when said ARTHUR F. UNDERWOOD.

